Substituted naphthacenes are known fluorescers and used extensively in the manufacture of chemiluminescent lighting devices in combination with oxalates and peroxide generators. Rubrene per se has been commercially available for many years and is generally produced by the reaction of 1,1,3-triphenylpropargyl alcohol and thionyl chloride with subsequent heating of the resultant reaction product in the presence of an amine base. Ofttimes, the rubrene is produced in the form of its sulfonate by reaction with fuming sulfuric acid. Yields of rubrene utilizing the above procedure, however, are relatively low, i.e., 30-50% and not very reproducible.
Other procedures for the production of rubrene are taught in Moureu et al; C.R. Acad. Sci. (1926), 182, 1440; Moureu et al; Bull. Soc. Chem. (1930), 216, Wittig et al; Journal fur praktische Chemie N.F. (1942), 160, 242; Rigaudy et al; Tetrahedron (1977), 33, 767. In each of the procedures set forth above, the yields range from 20-50% and ofttimes require the isolation and purification of intermediates.
Thus, the industry is always searching for new procedures which enable the recovery of naphthacenes in increased yields and without the need for intermediate isolation and purification.